Wireless Local Area Network (WLAN) devices, such as those conforming to the Institute for Electrical and Electronic Engineers (IEEE) 802.11 protocols, may associate with an access point (AP) to communicate with the network. Although association with the AP allows communication with other devices also present on the WLAN, often the device may use the AP as a gateway to access a Wide Area Network (WAN), such as the Internet. Particularly for mobile devices, the availability of APs within range and the quality of the communication links offered by such APs may vary. To improve user experience, it may be desirable for the device to periodically monitor the wireless environment for available APs and then associate with the AP that currently offers the best reception.
Conventionally, these capabilities are achieved through the use of roaming parameters. For example, the device may scan for other available APs at a defined roaming interval. During this process, if a candidate AP having better signal quality is discovered, the device may hand over the connection from the current AP to the candidate AP. Although it may be beneficial to identify APs that may offer improved link quality, the discovery process represents power expenditure and may require periods of unavailability in the context of the current WLAN when looking for APs operating on other channels. Typically, the roaming interval may have a fixed value designed to minimize roaming scans so that unnecessary power consumption is avoided and communication disruptions resulting from going off channel to perform the roaming scans are reduced.
However, the use of fixed roaming parameters does not accommodate certain use cases and may lead to undesirable performance characteristics. For example, in typical home environment, only one AP may be available. Thus, continual roaming scans may be performed even though no alternative APs exist. To address such situations, the roaming interval may be increased when no alternative APs are discovered. Although this may mitigate the power consumption, unnecessary scans may still be performed when no additional APs exist or an unnecessary delay in discovering a new AP may result if such an AP does become available.
Another conventional strategy for adjusting roaming parameters is based on the operational state of the device's processor. For example, applications running on the device processor may be the source or sink for data exchanged over the WLAN. Accordingly, the device processor being in suspend or other power saving mode may be taken as an indication that there is no demand for communication over WLAN, allowing roaming scans to be disabled on the assumption there is no current need for connectivity.
This strategy also has drawbacks because the operational state of the device processor may not accurately reflect actual demand for WLAN communications. For example, the device processor may be active when running an application that does not require WLAN traffic, such as playback of local media files, and more roaming scans than necessary may be conducted. In another example, data processing may be offloaded from the device processor to the WLAN transceiver, such that the WLAN transceiver processes data packets without involvement of the device processor, and it would be desirable for the WLAN connection to be optimized even though the processor is inactive. Further, many communication exchanges may be initiated at an external source. Even if the device processor is not currently being used, having a robust WLAN connection may reduce delays in receiving such communications. In these types of scenarios, the device processor operational state may not be a valid indication of WLAN roaming demand. For example, if the device processor is in power save mode, more desirable alternative APs may not be discovered, preventing or delaying incoming communications that may be delivered over the WLAN.
Accordingly, this disclosure is directed to dynamically adjusting one or more roaming parameters based, at least in part, on criteria corresponding to WLAN activity or connectivity characteristics. In turn, energy expended to discover alternative APs exhibiting more desirable performance characteristics may be balanced against demand for connectivity and current channel conditions.